Picked these up in my last order (Yes, I did ALOT of cat toys in that order! XD), and they were for my 4-week kitten. They're a bit too big for her to really whack well, but she loves them and is determined to make them roll. I love the happy little bell sound.. it's not a loud and jarring jangling, but a merry little tinkle noise that reminds me of Tinkerbell. Love them.
My daughters kept getting on me about how my cats were overweight. But they were right so I knew I had to do something to get them healthy. Since they are indoor cats, exercise was the first step, and these glitter balls got them moving right away! They love them and will bat them around for hours. Between these and the natural balance reduced calorie cat food, my three boys are zipping around the house like kittens again!
So I'm not sure if I'm allowed to promote them for "non-pet" uses, but I've cut them in half to use as "lifters" under the back edge of a laptop to help the fan vent better. Unbelievably cheap computer accessory, and the cats got the other 3 to lose under the sofa/fridge/stove...